The Feet Of The Apostles

Διατί τους πόδας μόνον, καὶ οὐχὶ ἕτερον μέλος τῶν μαθητῶν ὁ Κύριος ἔνιψιν; Ὅτι οὐ ῥύπον ἁπλῶς, καθάπερ νενόμικας, ἀπέκλυζεν ὁ Σωτὴρ, ἀλλὰ θείαν τινὰ δύναμιν ταῖς πτέρναις τῶν ἀποστόλων ἐνέβαλλεν. Ἐπειδὴ γὰρ εἴρηται τᾡ ὄφει, ὅτι Σὺ τηρήσεις τοῦ ἀνθρώπου τὴν πτέρναν, τουτέστι τὴν πᾶσαν τοῦ βίου διαγωγὴν, διὰ τοῦτο οἱ πόδες τῶν μαθητῶν πέπλυνται, ἐν τῷ συμβόλῳ δηλοῦντες τοὺς νοουμένους πόδας· Δέδωκα τοίνυν ἐξουσίαν ὑμῖν πατεῖν ἐπάνω ὄφεων, καὶ σκορπίων, καὶ ἐπὶ πᾶσαν τὴν δύναμιν τοῦ ἀοράτου ἐχθροῦ. Καὶ Ἡσαῗας λέγει· Ὡς ὡραῖοι οἱ πόδες τῶν εὐαγγελιζομένων εἰρήνυν καὶ ἀγαθά. Οἱ γὰρ δὴ τοῦ Χριστοῦ ἀπόστολοι κατέλυσαν μὲν τοῦ διαβόλου τὸν πόλεμον, πᾶσαν περιδραμόντες τὴν οἰκουμένην, εἰρήνην δὲ τοῖς πᾶσιν ἐβράβευσαν, καὶ εὐηγγελίσαντο ἡμῖν τὰ οὐράνια ἀγαθἀ. Ἅγιος Νειλος, Βιβλίον Πρῶτον, Ἐπιστολή Π' Φλαυιανῳ Source: Migne PG 79.117c

Why did the Lord wash only the feet of the disciples and not any other part? 1 Not only they were dirty, as you judge, which the Saviour cleansed, but He added Divine fortitude to the feet of the Apostles. For indeed it was said to the serpent, 'You shall watch for the heel of the man.' 2 that is, that which bears all life, whence the feet of the Apostles were washed as a sign expressing what should be thought of the feet: 'I have thus given you power to walk on serpents and scorpions, and on every power of the unseen enemy. 3 And Isaiah says: 'How beautiful are the feet of him announcing peace and good things.' 4 So the Apostles of Christ, travelling through the whole orb of the earth, trampled down the warring sinews of the devil, and gave peace to all, and proclaimed heavenly goods to us. Saint Nilus of Sinai, Book 1, Letter 80, To Flavianus 1 Jn 13.4-7 2 Gen 3.15 3 Lk 10.19  4 Isaiah 52.7